Device for adjusting the striking force of the type bars of electric typewriters



2,868,345 E OF THE ERS Jan. 13, 1959 B. TNITSCHKE DEVICE FOR ADJUSTING THE STRIKING FORC TYPE BARS 0F ELECTRIC TYPEWRIT Filed Oct. 25, 1956 V 2 Sheets-Sheet 1 Z Z Z WL Jan. 13, 1959 B. NITSCHKE 2,868,345

DEVICE FOR ADJUSTING THE STRIKING FORCE OF THE TYPE BARS OF ELECTRIC TYPEWRITERS Flled Oct 25, 1956 2 Sheets-Sheet 2 United States Patent Ofitice 2,868,345 Patented Jan. 13, 1959 7 DEVICE FOR ADJUSTING THE STRIKING FORCE OF THE TYPE BARS OF ELECTRIC TYPE- WRITERS Application October 25, 1956, Serial No. 618,295 3 Claims. (21. 197-11 In connection with electrically driven typewriters it its desirable to adjust the'typing force dependent upon the number of copies to be produced. This takes place by means of a manual setting lever of the striking rod of thedriving connection for the type-driving mechanism which is accomplished by regulating the time duration of the coupling contact with the driving cylinder. It is also desirable to regulate the striking force of the individual type elements in order to produce a clear impression depending upon the size of the letters. In this way the type elements on a type bar will be operated with the same force whether the element has small or large letters. Since in general the small letters have less contact surface than the large letters, the small letters, numerals and symbols will be more forcibly printed than the large letters so that the typing produces a nonuniform copy.

It is therefore an object of the invention to provide a setting device between the manual setting member and a stop rod so that the interval of contact with the power cylinder may be adjused at will and in dependence upon the typing of capital and small letters and symbols. A further object of the invention provides for an adjustment of the typing force by a change in the time interval of the contact with the power means.

Further objects will be apparent from the following description when considered in connection with the accompanying drawing in which:

Figure 1 is a perspective View of the structure according to the invention, and

Figure 2 is a side elevation partly in section of the drive for the typebars.

As shown in Fig. 1, a plate 3 is provided with a control cam slot 2 and is secured to swing on a bearing member 5, which latter is secured on the frame, not shown, of the machine by means of screws 6. A pin or rod 7 is guided in the control slot 2 and is screw-threaded into a rod 8. The part of the rod 8 which projects backwardly is provided with an elongated slot 9 into which a part of a stop rod 10 projects. The stop rod 10 is secured in two levers 11 each pivoted in a bearing point 12.

The forward part of the rod 8 is connected to a lever arm 14 by means of a screw 13, the arm 14 being pivotable around a bolt or pin 15. By means of a pin and slot connection 16 and 17, the lever arm 14 is connected with a manual setting member 18 pivoted to swing around the bolt or screw stud 19. The manual setting member 18 is provided with numerals to 6 which cooperate with a mark 20 as for example an arrow on the machine frame. The mark 20 together with the setting from 0 to 6 indicates the force of the type bar on the platen. If the 0 setting is adjacent the arrow 20, this indicates that the striking force of the type head 35 on the platen 36 will be the lowest force, whereas when the setting is on the numeral 6 relative to the arrow 20, the striking force of the type head is at the greatest force. By means of two screw-slot connections 21 and 22 the two parts of the rod 8 may be adjusted relative to each other.

The right-hand part of the rod 8, Fig. 1, is provided with a plurality of teeth 23 as a toothed rack which cooperates with a latch member 24 under the influence of a spring 25 whereby the rod 8, the arm 14 and the manual setting member 18 can be held in the adjusted position. The latch member 24 is pivoted around a screw pin or bolt 26 mounted on the bearing member 5. A shift lever 27 is pivotable around a bearing point 29 and a pin 28 connected thereto projects into a slot 1 in the plate 3. i i A controlling cam 31 is loosely and rotatably mounted on the drive shaft 30 which rotates constantly and said cam cooperates with two rollers 32 and 33 mounted on the switch lever 27. The controlling cam 31 is capable of being coupled to the shaft 30 in a suitable manner upon pressing down on a shift key, not shown.

' Upon adjusting the manual setting member 18 to rotate clockwise over the pin-slot connection 16 and 17, the lever arm 14 will be rotated clockwise around the pin 15. This will result in the rod 8 being shifted to the left, Fig. 1, and it will be held in the adjusted position by means of the latch member 24. By this adjustment the pin 7 will slide in the control slot 2 and this will result in the rod 8 being rotated counterclockwise around the screw 13. A swinging of the plate 3 around the screw 4 cannot now take place, since the pin 28 projecting into the slot 1 of the plate 3 will prevent this.

Upon the swinging of the rod 8 in the counterclockwise direction, the upper edge of the slot 9 of the rod 8 will contact the stop rod 10, whereby this and the lever 11 will be rotated in clockwise direction around the bearing point 12. This will result in that upon the depression of a key of the machine, the time interval for contact of the driving link 37 with the driving cylinder or roll 38 will be extended and striking force of the type head against the platen 36 will be increased.

In order to attain a uniform typing, it is necessary that the striking force of the type heads in typing capital letters shall be increased, since these as small letters and characters have a greater contact printing surface.

If the shift lever or key, not shown, of the key board is depressed for the purpose of typing capital letters, the cam disc 31 will be coupled by means of a coupling, not shown, to the drive shaft 30, so that it will take part in the rotation. Upon this rotation, the cam disc 31 rotates clockwise so that the larger part thereof will cooperate with the roller 32 of the shift lever 27 whereby this latter will be rotated clockwise around its bearing point 29. The pin 28 connected to the lever 27 will now contact on the lower surface of the slot 1 of the plate 3 and this plate will be rotated counterclockwise around the pin or stud 4. By this rotation, the upper edge or surface of the control slot 2 Will contact the pin 7 of the rod 8 and swing the latter counterclockwise around the screw 13. This will result in the contact of the upper edge of the slot 9 on the rod 8 forcing the stop rod 10 downwardly, whereby this and the lever 11 will rotate clockwise around the bearing point 12. This will result, upon the actuation of a type bar key 41 in increasing the interval of contact of the driving link 37 with the driving roller or cylinder 38 and thereby strengthening the blow of the type head on the platen. The advantage is thus attained that by a manual setting lever or device 18, the striking force of the type head can be increased as to the capital letters.

Upon the further movement of the rod 8 to the left, Fig. 1, the distance of the screw 7 from the pin 4 will be increased. Upon the swinging of the plate 3 around the pin 4 in counterclockwise direction upon the actuacompared with tion of the shift lever 27, the rod 8 will be swung downwardly around a greater angle. Thereby also the rod 10 will be swung a greater distance. Thus the drawback is taken into consideration that upon the setting of the manual setting lever 18 to a small typing force that only a small increase of the typing force is necessary when typing capital letters. If, however, a large typing force is set, as for example, when large number of carbon copies are required, then upon adjustment for large letters, a greater typing force will result.

As to the operation of the device the stop rod 19 is set in dependence upon the typing conditions required. Upon depressing a type key 41, the double-armed lever 42 will be actuated when the link 37 is rotated counter clockwise to contact the driving roller 38. This will re sult in a pull on the link 43 which latter will swing the lever 44 to the right and by means of the pull rod 45, the respective type bar 46 will be swung upwardly so that the type head 35 will contact the platen 36.

I claim as my invention:

1. In an electrically driven typewriter, a device for adjusting the striking force of the type heads by adjusting the interval of contact of a drive link with a rotating cylinder, comprising a manual setting member, a stop rod, a shift lever, and means connected to the setting member, the shift lever and the stop rod to adjust the stop rod and thereby the typing force of the type heads, said means comprising a pivotally-mounted member having a guiding slot, a pin connected with the setting member and slidable in the guiding slot, and means for swinging the second-mentioned member by the shift lever about its pivotal mounting.

2. An electrically driven typewriter according to claim 1, in which the pivotally-mounted member is in the form of a plate with the guiding slot therein.

3. An electrically driven typewriter according to claim 1, in which the guiding slot is so arranged that the difierence of adjustment of the stop rod by the shift lever is diminished by adjusting the setting member for minor typing force.

References Cited in the file of this patent UNITED STATES PATENTS 

